The Brookhaven Synchrotron X-Ray Microprobe Research Resource uses high-energy x-rays produced by the National Synchrotron Light Source (NSLS) for sensitive trace-element analysis and imaging in various types of biological structures. The NSLS is a uniquely bright source of x-rays and thereby serves as the foundation of the Resources which is presently unsurpassed at any other location. The aim of the Resource is to combine scientists from the life and physical sciences in a multidisciplinary effort to push the potentialities of synchrotron radiation for elemental x-ray fluorescence measurements to (1) the furthest possible limits in terms of sensitivity, spatial resolutions, and chemical form of the elements examined and (2) to carry on an extensive biological research program to exploit the results of the technical development program. Other Brookhaven nuclear facilities are used to complement the features of the photon beams at the NSLS so as to provide other nuclear analytical techniques when necessary. The complete facility fills the gap between high resolution electron microscopy and bulk analysis techniques. The combination of the synchrotron with computed tomography techniques extends the possibilities of tomography into many new research regions. This Resource uses radiation from a bending magnet to provide filtered white light or monochromatic radiation. The addition of focussing mirrors to the system will give higher fluxes at the target and increase the sensitivity of the determinations. Two different types of mirrors are planned: a simple 1:1 cylindrical mirror and an 8:1 ellipsoidal mirror which focusses in two dimensions. The goal is to obtain detection sensitivities less than 50-100 ppb (by weight) in a 10- to 20-magnetic moment. The Resource presently can be used with a spot size of 25 magnetic moment, and a detection sensitivity around 200 ppb for elements around iron. The initial biological research effort is aimed at studying several aspects of trace element biology and toxicology: (1) trace element localization in the hepatic lobule, (2) trace element interactions, (3) trace element analysis of rodent cerebellium, (4) sterological analysis of microprobe data, and (5) in-vivo analysis of lead in the tibia. A number of collaborative projects in related analytical and biological fields are in progress with scientists from other institutions. A service program is operated to make sure that the Resource can be used freely by all qualified and interested scientists. The new features of the Resource are made known by a regular series of workshops and symposia and seminars presented by the Resource staff.